The present invention relates to composite wood panels each having a tongue edge and a groove edge, the tongue and groove edges being complementary to permit interconnection of the panels. In particular, the present invention relates to wood panels having tongue and groove edges and means for maintaining a space between panels when the tongue of one panel is engaged with the groove of another.
Interconnecting tongue and groove wood panels or boards are well known and widely used in the construction industry. These panels are commonly constructed from plywood, particleboard, waferboard, strandboard or other composite wood product materials. Tongue and groove composite wood panels are particularly well suited for installation on a joist framing assembly because the interlocking edges of the panels reduce vertical offset between adjacent panels, thereby providing a smoother structural sub-floor. In addition, the load carrying transfer along the interconnected edges prevents relative movement between adjacent panel edges as persons walk along the floor, thereby reducing floor squeaking. Typically, carpet, tile or a hardwood is installed over a structural sub-floor to provide a finished floor surface.
While tongue and groove composite wood panels are generally very useful, such composite panels commonly swell and expand due to the absorption of moisture by the panel. This expansion causes the interconnected edges of the adjacent wood panels to press tightly against one another creating stress along the panel edges. As a result, the interconnected wood panels begin to buckle and bow. In addition, the stress along the panel edges can cause undesirable popping, cracking or squeaking when persons step upon or near the joints.
Accordingly, there is a need in the building industry for tongue and groove wood panels which reduce unwanted stress along the interconnected panel edges during panel expansion, while continuing to reduce vertical offset and provide effective load carrying transfer along the length of the tongue and groove joint.
In summary, the invention relates to a composite wood panel comprising a first and second longitudinal edge, wherein the first edge includes a groove and the second edge includes a tongue, for interlocking and engaging the complementary edges of adjacent tongue and groove wood panels. Preferably, the groove has two sides and a base transverse thereto, and the tongue has two side walls and a head extending outward from the second longitudinal edge, thereby forming a juncture between the side walls of the tongue and the second longitudinal edge. A shoulder is located at the juncture between one side wall of the tongue and the second longitudinal edge. Upon assembly of two complementary wood panels to form a tongue and groove joint, the shoulder will abut the first longitudinal edge, thus preventing the tongue from being completely introduced into the complementary groove. As a result, an aperture is formed between the head of the tongue and the base of the groove. Further, an aperture is formed between the first and second longitudinal edge both above and below the engaged tongue and groove.
The apertures allow for subsequent expansion and swelling along the longitudinal edge of the interconnected panels. Particularly, the shoulder will deform or compress as the interconnected panels expand, thereby reducing stress along the edges of the interconnected panels. Accordingly, as the wood panels expand and swell due to the absorption of moisture, undesired stress along the longitudinal edges of the interconnected composite wood panels is reduced or eliminated.
In this way, the invention provides high strength tongue and groove composite wood panels which may be utilized in flooring or sub-flooring assembly free of buckling, bowing or cracking resulting from stress and pressure along the interconnected wood panel edges. Further, the reduction of stress along the edges of interconnected wood panels will reduce the undesired popping or squeaking due to persons walking along or near the panel joints.